The present invention has particular utility in connection with the industrial, military, and scientific application of lasers and is described herein as applied to such use. In recent years, lasers have been enjoying an ever increasing range of applicability to various processes. The word "laser" is an acronym for "light amplification by stimulated emission of radiation." Therefore, a laser is basically a device for the generation of coherent, nearly single wavelength and frequency, highly directional electromagnetic radiation.
Currently, the gas CO.sub.2 (carbon dioxide), and the solid state Nd:YAG (Yttrium, Aluminum, Garnet) lasers dominate the material cutting and welding industries. However, the applicability of these lasers in a wide variety of manufacturing processes is limited. The gas CO.sub.2 laser, because of the beam's long wavelength, and the Nd:YAG laser because of its low brightness, both require a great deal of power to be useful. Brightness, also called the beam quality compares the relative amount of energy within the central lobe of a laser beam with that of a perfect laser beam. The numbers corresponding to brightness are greater than or equal to unity, with values of 1 indicating superior brightness and values much greater than 2 or 3 indicating poor performance.
Due to its high brightness and small wavelength, the photolytic iodine laser (PIL) has the potential to address the needs of a wide variety of markets. The PIL is a gas laser which employs a gas as a fuel for generating the laser beam. Usable PILs were first developed in the early 1980's. However, these early PILs were not suitable for manufacturing processes. They displayed poor output power as compared to input power, as well as poor repeatability of performance. Additionally, these early systems were prone to excessive buildup of molecular iodine which severely interrupted the lasing process.
PILs require a continuous flow of fuel through the laser's gain cell region in order to generate a laser beam. The laser's gain cell is that section of the laser where light amplification occurs. For a given gain cell size, the laser's power is proportional to the flow rate of the gaseous fuel through the gain cell. Conventional PILs have employed blowers in the fuel delivery system to provide adequate fuel flow rates. However, these blowers can be costly. In addition, it has been found that merely increasing the pressure in the system is not sufficient. The types of fuel employed in PILs, namely C.sub.3 F.sub.7 I, exhibit high frictional properties which basically cause the fuel to "stick" to the walls of the conduits within which the fuel flows. This results in significant pressure drops in the fuel system thereby making it difficult to establish and maintain fuel flow rates sufficient to generate a laser beam of proper intensity.
PILs employ microwave systems to provide power to the lamps needed to generate a laser beam. In the past, these systems utilized low power magnetrons as the power source. Therefore, these systems required large numbers of magnetrons; one for each lamp, and extensive supporting systems, to provide for adequate laser power. The microwave systems were very complex and required a great deal of maintenance. This made these lasers impractical for industrial use.
Therefore, it is important to provide a PIL whereby the components are kept simple, and the number of components is kept to a minimum. This will allow for ease of maintenance, as well as make the laser more competitive with conventional material processing equipment.
In view of the foregoing, there is a current need and large market potential for an economical materials processing laser which is superior in both brightness, and processing performance to those currently in use. Moreover, the laser must be capable of maintaining its performance integrity over extended periods of time.
Therefore, the general object of the present invention is to provide a continuous wave laser for use in industrial applications which can be economically procured and operated, yet is capable of generating a laser beam of sufficient power so as to be practical.
It is a further object of the present invention to provide a CW PIL which does not require the use of expensive blowers to maintain the fuel flow rate.
It is yet another object of the present invention to provide a PIL wherein the microwave system is capable of powering more than one lamp on a single magnetron.
It is still a further object of the present invention to provide a method for determining critical laser parameters.